Method of obtaining refrigeration at cryogenic level

Abstract

A method of obtaining refrigeration at a cryogenic level comprising a gaseous fluid fed in the form of an incoming stream to sustain a refrigerative load. The incoming stream is stepwise cooled and expanded with liquefaction. The liquid fluid formed is used to sustain a refrigerative load, evaporating as a consequence, and the vapour constitutes a return stream which is adiabatically compressed so as to attain a temperature close to the temperature of the incoming stream before the liquefaction thereof.

What is claimed is: 
     
       1. A method of obtaining refrigeration at cryogenic level comprising compressing a gaseous fluid constituting an incoming stream, stepwise cooling the incoming stream, expanding the incoming stream with its liquefaction, feeding the liquid fluid so formed to sustain at least one refrigerative load wherein the liquid is transformed into vapour constituting a return stream flowing back from the refrigerative load sustained, and adiabatically compressing the return stream flowing back from the refrigerative load so as to attain a temperature close to the temperature of the incoming stream before the expansion thereof with liquefaction; said stepwise cooling of the incoming stream being effected with said return stream. 
     
     
       2. A method of obtaining refrigeration as claimed in claim 1, wherein the return stream is warmed up with the expanded incoming stream before being adiabatically compressed. 
     
     
       3. A method of obtaining refrigeration wherein sustained are at least two successively arranged refrigerative loads flowing through each of which is a separate return stream of gaseous fluid as claimed in claim 1, and wherein the return stream outflowing from a preceeding refrigerative load is subject, before being adiabatically compressed, to a heat exchange with the return stream outflowing from a succeeding refrigerative load after the adiabatic compression thereof. 
     
     
       4. A method of obtaining refrigeration as claimed in claim 3, wherein the return stream outflowing from the succeding refrigerative load is warmed up with the incoming stream of said fluid before being adiabatically compressed. 
     
     
       5. A method of obtaining refrigeration as claimed in claim 3, wherein the gaseous fluid constituting the stream of the succeeding refrigerative load is helium-3, an isotope of helium.